Example: biology

IPC-7095C Design and Assembly Process …

IPC-7095C Design and Assembly Process Implementation for BGAs Developed by the IPC Ball Grid Array Task Group (5-21f) of the Assembly & Joining Processes Committee (5 ...

Information

Domain:

Source:

Link to this page:

Please notify us if you found a problem with this document:

Other abuse

Text of IPC-7095C Design and Assembly Process …

IPC-7095CDesign andAssembly ProcessImplementationfor BGAsDeveloped by the IPC Ball Grid Array Task Group (5-21f) of theAssembly & Joining Processes Committee (5-20) of IPCUsers of this publication are encouraged to participate in thedevelopment of future :IPC3000 Lakeside Drive, Suite 309SBannockburn, Illinois60015-1249Tel 847 847 :IPC-7095B - March 2008IPC-7095A - October 2004IPC-7095 - August 2000 Table of ........................................ ......................... ........................................ ............................ 12APPLICABLE ........................................ ............................... ........................................ .......................... 23SELECTION CRITERIA AND MANAGING of Infrastructure ............................... Patterns and Circuit BoardConsiderations ........................................ .............. Comparison ...................................... Equipment Impact .............................. Requirements ........................................ ... Requirements ..................................... ........................................ ............................... Readiness .................................. ........................................ ................ Step Analysis ........................................ .. Limitations and Issues ............................... Inspection ........................................ ....... Sensitivity ........................................ ... Unbalanced BGA Design ................ ........................................ ....................... ........................................ ............................ ........................................ ................. in BGA ........................................ ............. Cratering ........................................ ............. Issues ....................................... Reliability Concerns ........................................ .. Drivers for Lead-Free Technology .................... 144COMPONENT Packaging Comparisons andDrivers ........................................ ........................ Feature Comparisons ........................... Package Drivers ....................................... Issues ........................................ ................. Handling ........................................ . Performance ........................................ Estate ........................................ ................. Performance ....................................... Performance ................................... Mounting in the BGA Package .................. Bond ........................................ .................. Chip ........................................ .................... ........................................ ........... Standards for BGA .............................. Pitch ........................................ ................... Package Outline ....................................... Size Relationships ...................................... BGA ................................. ........................................ ................. Packaging Style Considerations .... Ball Alloy ........................................ ....... Attach Process ........................................ .... Ball Grid Array ................................... Column Grid Arrays ........................... Ball Grid Arrays ....................................... Die Packaging ..................................... (SiP) ................................... Folded Package Technology ........................ Stack, Package-on-Package ....................... and Stacked Packaging Combination ... ........................................ .. of Multiple Die Packaging .................. Solutions for Very Fine Pitch ArrayPackaging ........................................ ................... Connectors and Sockets ........................... Considerations for BGAConnectors ........................................ ................. Considerations for BGAConnectors ........................................ ................. Materials and Socket Types ..................... Considerations for BGASockets ........................................ ....................... Construction Materials ............................. of Substrate Materials ............................. of Substrate Materials ...................... Package Design Considerations ............... and Ground Planes ................................. Integrity ........................................ .......... Spreader Incorporation Inside thePackage ........................................ ...................... Package Acceptance Criteria andShipping Format ........................................ ........ Balls ........................................ ............. in Solder Balls ........................................ . 34January Ball Attach Integrity .............................. and Ball Coplanarity ........................... Sensitivity (Baking, Storage,Handling, Rebaking) ........................................ .. Medium (Tape and Reel, Trays,Tubes) ........................................ ......................... Ball Alloy ........................................ ....... 375PRINTED BOARDS AND OTHER of Mounting Structures ........................... Resin Systems ...................................... Structures ........................................ ... (Multilayer, Sequential orBuild-Up) ........................................ ................... of Mounting Structures .................... Systems ........................................ ............ ........................................ .......... Material Properties ............................ Finishes ........................................ ......... Air Solder Leveling (HASL) ..................... Surface Protection (OrganicSolderability Preservative) OSP Coatings ........ Platings/Coatings .................................... Mask ........................................ ............... and Dry Film Solder Masks ...................... Solder Masks .......................... Solder Mask ........................................ . of Board to Panel Image forSolder Mask ........................................ ............... Protection ........................................ ............ Spreader Structure Incorporation( , Metal Core Boards) .................................. Sequences ....................................... Transfer Pathway ...................................... 486PRINTED CIRCUIT ASSEMBLY Placement and Clearances ............. and Place Requirements ............................ Requirements ............................ Placement ........................................ ....... Legends (Silkscreen, CopperFeatures, Pin 1 Identifier) .................................. Sites (Land Patterns and Vias) ...... vs. Small Land and Impact on Routing ..... Mask vs. Metal Defined LandDesign ........................................ ........................ Width ........................................ ........ Size and Location ....................................... and Conductor Routing Strategies ........ Strategies ........................................ ....... Conductor Details ................................. Bone Through Via Details ........................ for Mechanical Strain ........................... Via-in-Pad and Impact onReliability Issues ........................................ ........ Pitch BGA Microvia in Pad Strategies ..... and Ground Connectivity ....................... of Wave Solder on Top Side BGAs ..... Side Reflow ........................................ ........ of Top Side Reflow ............................... of Avoiding Top Side Reflow ............ Side Reflow for Lead-Free Boards ............ and Test Point Access ...................... Testing ........................................ .... to the Solder Balls During Test andBurn-In ........................................ ....................... Board Testing ........................................ .... Testing ........................................ ....... Design for Manufacturability Issues ....... Design ........................................ .... Product Test Coupons .............. Management ........................................ ........................................ ................. ........................................ .................... ........................................ ................. Interface Materials .............................. Sink Attachment Methods for BGAs ....... and Electronic Data Transfer ... Requirements ...................................... Messaging Protocols ....................... ........................................ ............. 757ASSEMBLY OF BGAS ON PRINTED Assembly Processes .................................. Paste and Its Application ....................... Placement Impact ........................... Systems for Placement ........................... Soldering and Profiling ......................... Issues ........................................ ........... Phase ........................................ ............... vs. No-Clean ...................................... Standoff ........................................ ....... Processes ........................................ .. Coatings ........................................ ... 86IPC-7095CJanuary of Underfills and Adhesives ....................... of Boards and Modules ................. Techniques ........................................ Usage ........................................ .............. Image Acquisition .................................. and Discussion of X-Ray SystemTerminology ........................................ ............... of the X-Ray Image ........................... Acoustic Microscopy ......................... Standoff Measurement ............................. Inspection ........................................ ...... Analysis Methods ........................... and Product Verification ..................... Testing ........................................ ..... Coverage ........................................ .......... Testing ........................................ ........ Screening Tests .................................. Identification ........................................ ... of Voids ........................................ ...... Classification ........................................ ... in BGA Solder Joints ............................ Measurement ........................................ ... Detection and MeasurementCautions ........................................ ................... of Voids ........................................ ........ Protocol Development ............................ Plans for Void Evaluation ............... Control for Void Reduction ............... Parameter Impact on VoidFormation ........................................ ................. Control Criteria for Voids inSolder Balls ........................................ .............. Control Criteria .................................. Defects ........................................ .......... Bridging ........................................ ........ Solder ........................................ .............. ........................................ ....................... Heating ............................ ........................................ ........ Ball/Non-Wet Open (NWO) ............. Defects ........................................ .. Correlation/Process Improvement ....... Processes ........................................ ...... Philosophy .............................. of BGA ........................................ ..... ........................................ ............. Drivers for BGAs .......................... strain ........................................ ............. ........................................ ...................... ........................................ ........................ and Fatigue Interaction ......................... reliability ...................................... Mechanisms and Failure of SolderAttachments ........................................ .............. of Thermal Fatigue CrackGrowth Mechanism in SAC vs. Tin/LeadBGA Solder Joints ........................................ ... Alloy Soldering .................................... Joints and Attachment Types ............... Expansion Mismatch ........................... Expansion Mismatch ............................. Expansion Mismatch .......................... Attachment Failure ............................... Attachment Failure Classification ........ Signature-1: Cold Solder .................... Signature-2: Land, Nonsolderable ...... Signature-3: Ball Drop ........................ Signature-4: Missing Ball ................... Signature-5: PCB and BGA StackWarpage ........................................ .................... Signature-6: Mechanical Failure ......... Signature-7: Insufficient Reflow ......... Factors to Impact Reliability ............. Technology ........................................ Height ........................................ ...... Design Considerations ............................ of Solder Attachments ofCeramic Grid Array ........................................ . Soldering of BGAs ........................ for Reliability (DfR) Process .............. and Qualification Tests .................. Procedures ....................................... Joint Defects ........................................ . Recommendations ........................... Reliability Testing ....................... 1369DEFECT AND FAILURE ANALYSIS Mask Defined BGA Conditions ........... Mask Defined and NondefinedLands ........................................ ........................ Mask Defined Land on ProductBoard ........................................ ........................ Mask Defined BGA Failures ............... 139January BGA Solder Ball Conditions .. Ball Shape without Heat Slug500 m Standoff Height .................................. Ball Shape with Heat Slug 375 mStandoff Height ........................................ ........ Ball Shape with Heat Slug 300 mStandoff Height ........................................ ........ Solder Paste Conditions ..................... Thick Paste Deposit ............................ Determination Through X-Ray andCross-Section ........................................ ........... and Uneven Solder Balls ...................... Void ........................................ ........... Interposer Bow and Twist ...................... Interposer Warp ...................................... Joint Opens Due to Interposer Warp ... Joint Conditions ................................... Solder Condition .................................. Balls with Excessive Oxide ................. of Dewetting .................................... Condition ........................................ .... Solder Ball Evaluation ..................... Alloy ........................................ ................ Solder Joint ........................................ ..... Joining Due to LandContamination ........................................ .......... Solder Ball Contamination ............. Solder Ball ...................................... Insufficient Solder and Flux for Proper JointFormation ........................................ ................. Termination Contact Area ................ Bridging ........................................ ........ Solder Reflow ............................... Solder ........................................ ......... Open (NWO) Solder Joint ................. (HoP) Solder Joint ................ 14710GLOSSARY AND 14811BIBLIOGRAPHY AND 150Appendix AProcess Control Characterization toReduce the Occurrence of 151FiguresFigure 3-1BGA Package Manufacturing Process ............. 3Figure 3-2Area Array I/O Position Comparisons .............. 5Figure 3-3Area Array I/O Position Patterns ...................... 5Figure 3-4MCM Type 2S-L-WB ........................................ . 6Figure 3-5Conductor Width to Pitch Relationship ............ 7Figure 3-6Plastic Ball Grid Array, Chip Wire Bonded ....... 8Figure 3-7Ball Grid Array, Flip Chip Bonded .................... 8Figure 3-8BGA Warpage ........................................ ......... 11Figure 3-9Examples of Pad Cratering ............................ 13Figure 3-10Various Possible Failure Modes for a BGASolder Joint ........................................ ............. 13Figure 4-1Termination Types for Area Array Packages .. 16Figure 4-2BOC BGA Construction .................................. 18Figure 4-3Top of Molded BOC Type BGA ...................... 18Figure 4-4Flip-Chip (Bumped Die) on BGA Substrate ... 19Figure 4-5JEDEC Standard Format for Package-on-Package Components .................................... 22Figure 4-6Polymer Coated Sphere Interconnection ....... 23Figure 4-7Plastic Ball Grid Array (BGA) Package .......... 24Figure 4-8Cross-Section of a Thermally EnhancedCeramic Ball Grid Array (CBGA) Package ..... 25Figure 4-9Ceramic Ball Grid Array (CBGA) Packagewith Molded Polymer Encapsulation .............. 25Figure 4-10Ceramic-Based Column Grid Array (CCGA)Package ........................................ .................. 26Figure 4-11Polyimide Film-Based Lead-Bond BGAPackage Substrate Furnishes CloseCoupling Between Die Pad and BallContact ........................................ ................... 26Figure 4-12Comparing In-Package Circuit RoutingCapability of the Single Metal LayerTape Substrate to Two Metal LayerTape Substrate ........................................ ....... 26Figure 4-13Single Package Die-Stack BGA ..................... 27Figure 4-14Custom Eight Die (Flip-Chip andWire-Bond) SiP Assembly .............................. 27Figure 4-15Folded Multiple-Die BGA Package ................. 27Figure 4-16Eight Layer Ball Stack Package ..................... 27Figure 4-17SO-DIMM Memory Card Assembly ................ 28Figure 4-18Folded and Stacked Multiple DieBGA Package ........................................ ......... 28Figure 4-19Package-on-Package Assembly ..................... 28Figure 4-20Semiconductors Packaged with PILR Substrate ........................................ ..... 29Figure 4-21Solder Interface Between PILR-ConfiguredSubstrate Interposer and Circuit Board .......... 29Figure 4-22BGA Connector ........................................ ....... 29Figure 4-23PGA Socket Pins ........................................ .... 30Figure 4-24PGA Socket With and Without Pick andPlace Cover ........................................ ............ 30Figure 4-25LGA Contact Pin ........................................ ..... 31Figure 4-26LGA Socket With and Without Pick andPlace Cover ........................................ ............ 31Figure 4-27Example of Missing Balls on a BGAComponent ........................................ ............. 35Figure 4-28Example of Voids in Eutectic Solder Ballsat Incoming Inspection ................................... 35Figure 4-29Examples of Solder Ball/Land SurfaceConditions ........................................ ............... 35Figure 4-30Establishing BGA Coplanarity Requirement ... 36IPC-7095CJanuary 2013viiiFigure 4-31Ball Contact Positional Tolerance ................... 36Figure 5-1Examples of Different Build-UpConstructions ........................................ .......... 38Figure 5-2Expansion Rate Above 40Figure 5-3Hot Air Solder Level (HASL) SurfaceTopology Comparison ..................................... 42Figure 5-4Black Pad Related Fracture Showing CrackBetween Nickel & Ni-Sn Intermetallic Layer .. 43Figure 5-5Crack Location for a) Black Pad RelatedFailure and (b) Interfacial Fracture WhenUsing ENIG Surface Finish ............................ 43Figure 5-6Typical Mud Crack Appearance of BlackPad Surface ........................................ ............ 44Figure 5-7A Large Region of Severe Black Pad withCorrosion Spikes Protruding into NickelRich Layer through Phosphorus RichLayer Underneath Immersion GoldSurface ........................................ ................... 44Figure 5-8Gold Embrittlement ........................................ . 45Figure 5-9Graphic Depiction of Electroless Nickel/Electroless Palladium/Immersion Gold ........... 45Figure 5-10Graphic Depiction of Directed ImmersionGold ........................................ ........................ 45Figure 5-11Example of Micro Voids .................................. 46Figure 5-12Via Plug Methods ........................................ ... 49Figure 5-13Metal Core Board Construction Examples ..... 50Figure 6-1BGA Alignment Marks .................................... 51Figure 6-2Solder Lands for BGA Components ............... 53Figure 6-3Metal Defined Land Attachment Profile .......... 53Figure 6-4Solder Mask Stress Concentration ................. 53Figure 6-5Solder Joint Geometry Contrast ..................... 54Figure 6-6Good/Bad Solder Mask Design ...................... 55Figure 6-7Examples of Metal-Defined Land ................... 55Figure 6-8Quadrant Dog Bone BGA Pattern .................. 55Figure 6-9Square Array ........................................ ........... 56Figure 6-10Rectangular Array ........................................ ... 56Figure 6-11Depopulated Array ........................................ .. 56Figure 6-12Square Array with Missing Balls ..................... 56Figure 6-13Interspersed Array ........................................ .. 57Figure 6-14Conductor Routing Strategy ........................... 58Figure 6-15BGA Dogbone Land Pattern PreferredDirection for Conductor Routing ..................... 59Figure 6-16Preferred Screw and Support Placement ...... 59Figure 6-17Connector Screw Support Placement ............ 59Figure 6-18Cross Section of mm Ball with Via-in-Pad Structure (Indent to the Upper Left ofthe Ball is an Artifact.) .................................... 59Figure 6-19Cross Section of Via-in-Pad DesignShowing Via Cap and Solder Ball .................. 60Figure 6-20Via-in-Pad Process Descriptions .................... 60Figure 6-21Microvia Example ........................................ ... 61Figure 6-22Microvia-in-Pad Voiding .................................. 61Figure 6-23Ground or Power BGA Connection ................ 61Figure 6-24Example of Top Side Reflow Joints ................ 62Figure 6-25Example of Wave Solder TemperatureProfile of Topside of Mixed ComponentAssembly ........................................ ................ 62Figure 6-26Heat Pathways to BGA Solder Joint DuringWave Soldering ........................................ ...... 63Figure 6-27Methods of Avoiding BGA Topside SolderJoint Reflow ........................................ ............ 63Figure 6-28An Example of a Side Contact Made witha Tweezers Type Contact ............................... 64Figure 6-29Pogo-Pin Type Electrical ContactImpressions on the Bottom of aSolder Ball ........................................ .............. 65Figure 6-30Area Array Land Pattern Testing .................... 66Figure 6-31Board Panelization ........................................ . 69Figure 6-32Comb Pattern Examples ................................ 70Figure 6-33Heat Sink Attached to a BGA with anAdhesive ........................................ ................. 72Figure 6-34Heat Sink Attached to a BGA with a Clipthat Hooks onto the Component Substrate .... 72Figure 6-35Heat Sink Attached to a BGA with a Clipthat Hooks into a Through-Hole on thePrinted Circuit Board ...................................... 72Figure 6-36Heat Sink Attached to a BGA with a Clipthat Hooks onto a Stake Soldered in thePrinted Circuit Board ...................................... 73Figure 6-37Heat Sink Attached to a BGA by WaveSoldering Its Pins in a Through-Hole inthe Printed Circuit Board ................................ 73Figure 7-1Aspect and Area Ratios for CompletePaste Release ........................................ ........ 77Figure 7-2High Lead and Eutectic Solder Ball andJoint Comparison ........................................ .... 78Figure 7-3Example of Peak Reflow Temperatures atVarious Locations at or Near a BGA .............. 79Figure 7-4Schematic of Reflow Profile for Tin/LeadAssemblies ........................................ ............. 81Figure 7-5An Example of Tin/Lead Profile withMultiple Thermocouples .................................. 81Figure 7-6Schematic of Reflow Profile for Lead-FreeAssemblies ........................................ ............. 81Figure 7-7Examples of Lead-Free Profiles with Soak(Top) and Ramp to Peak (Bottom) withMultiple Thermocouples. The Profileswith Soak Tend to Reduce Voids inBGAs. ........................................ ..................... 82Figure 7-8Locations of Thermocouples on a Boardwith Large and Small Components ................ 82Figure 7-9Recommended Locations of Thermocoupleson a BGA ........................................ ................ 82Figure 7-10Effect of Having Solder Mask Relief Aroundthe BGA Lands of the Board .......................... 86Figure 7-11Map of Underfill Adhesive Usage for BGAand Other Packages ....................................... 88Figure 7-12Flow of Underfill Between Two ParallelSurfaces ........................................ .................. 88Figure 7-13Examples of Underfill Voids - small, mediumand large; upper left, lower left and left ofsolder balls, respectively ................................ 89January 2013IPC-7095CixFigure 7-14Example of Partial Underfill - package waspulled from the PCB and dark underfill canbe seen in the corners ................................... 89Figure 7-15Corner Applied Adhesive ................................ 90Figure 7-16Critical Dimension for Application ofPrereflow Corner Glue .................................... 90Figure 7-17Typical Corner Glue Failure Mode in Shockif Glue Area is Too Low - Solder Mask RipsOff Board and Does Not Protect the SolderJoints ........................................ ...................... 90Figure 7-18Fundamentals of X-Ray Technology .............. 92Figure 7-19X-Ray Example of Missing Solder Balls ........ 92Figure 7-20X-ray Example of Voiding in Solder BallContacts ........................................ .................. 92Figure 7-21Manual X-Ray System Image Quality ............ 92Figure 7-22Example of X-Ray Pin Cushion Distortionand Voltage Blooming .................................... 93Figure 7-23Transmission image (2D) ............................... 93Figure 7-24Tomosynthesis image (3D) ............................. 93Figure 7-25Laminographic Cross-Section Image (3D) ..... 94Figure 7-26Transmission Example ................................... 94Figure 7-27Oblique Viewing Board Tilt ............................. 94Figure 7-28Oblique Viewing Detector Tilt ......................... 94Figure 7-29Top Down View of FBGA Solder Joints .......... 95Figure 7-30Oblique View of FBGA Solder Joints ............. 95Figure 7-31Tomosynthesis ........................................ ........ 96Figure 7-32Scanned Beam X-Ray Laminography ............ 96Figure 7-33Scanning Acoustic Microscopy ....................... 97Figure 7-34Endoscope Example ....................................... 98Figure 7-35Lead-Free mm Pitch BGA Reflowedin Nitrogen and Washed Between SMTPasses ........................................ .................... 98Figure 7-36Lead-Free BGA Reflowed in Air andWashed Between SMT Passes ...................... 98Figure 7-37Engineering Crack Evaluation Technique ....... 99Figure 7-38A Solder Ball Cross Sectioned Througha Void in the Solder Ball ............................... 100Figure 7-39Cross-Section of a Crack Initiation at theBall/Pad Interface ........................................ . 100Figure 7-40No Dye Penetration Under the Ball .............. 100Figure 7-41Corner Balls have 80-100% DyePenetration Which Indicate a Crack ............. 100Figure 7-42Small Voids Clustered in Mass at theBall-to-Land Interface ................................... 102Figure 7-43Typical Size and Location of VariousTypes of Voids in a BGA Solder Joint .......... 103Figure 7-44X-Ray Image of Solder Balls with Voidsat 50 kV (a) and 60 kV (b) ........................... 104Figure 7-45Examples of Suggested Void Protocols ....... 105Figure 7-46Example of Voided Area at Land andBoard Interface ........................................ ..... 108Figure 7-47X-Ray Image Showing Uneven Heating ....... 110Figure 7-48X-Ray Image at 45 Showing InsufficientHeating in One Corner of the BGA ............... 110Figure 7-49Example of Head-on-Pillow Showing Balland Solder Paste have not Coalesced ......... 110Figure 7-50Head-on-Pillow Process SequenceOccurrences ........................................ .......... 111Figure 7-51HoP Due to High Package Warpage ............ 111Figure 7-52Example of Liquidus Time Delay .................. 111Figure 7-53Solder Particles on Board NoncoalescedAfter Reflow ........................................ ........... 111Figure 7-54Hanging Ball Examples ................................. 112Figure 7-55X-Ray Image of Popcorning ......................... 112Figure 7-56X-Ray Image Showing Warpage in a BGA .. 113Figure 7-57BGA/Assembly Shielding Examples ............. 114Figure 8-1BGA Solder Joint of Eutectic Tin/Lead SolderComposition Exhibiting Lead Rich (Dark)Phase and Tin Rich (Light) Phase Grains ... 120Figure 8-2Socket BGA Solder Joints of SnAgCuComposition, Showing the Solder JointComprised of 6 Grains (Top Photo) anda Single Grain (Bottom Photo). .................... 120Figure 8-3Thermal-Fatigue Crack Propagationin Eutectic Tin/Lead Solder Joints ina CBGA Module ........................................ .... 120Figure 8-4Thermal-Fatigue Crack Propagationin Joints in a CBGAModule ........................................ .................. 120Figure 8-5Incomplete Solder Joint Formation for1% Ag Ball Alloy Assembled at LowEnd of Typical Process Window ................... 122Figure 8-6Solder Joint Failure Due to Silicon andBoard CTE Mismatch ................................... 123Figure 8-7Grainy Appearing Solder Joint ..................... 124Figure 8-8Nonsolderable Land (Black Pad) ................. 124Figure 8-9Land Contamination (Solder MaskResidue) ........................................ ............... 124Figure 8-10Solder Ball Drop ........................................ ... 124Figure 8-11Missing Solder Ball ....................................... 125Figure 8-12Example of Dynamic Warpage of FlipChip BGA Packages and PCBs ................... 125Figure 8-13Example of a Severely Warped BGAPackage and PCB After Reflow Solderingin an Un-Optimized SMT Process ................ 125Figure 8-14Examples of Acceptable Convex SolderJoints with Solder Joint Surface TangentsShown in the Top Left Photo ........................ 126Figure 8-15Example of an Acceptable ColumnarSolder Joint ........................................ ........... 126Figure 8-16Two Examples of Pad Cratering (Locatedat Corner of BGA) ........................................ 127Figure 8-17Pad Crater Under mm Pitch Lead-Free Solder Ball. Crack in Metal TraceConnected to the Land is Clear; However,the Pad Crater is Difficult to See in BrightField Microscopy. ........................................ .. 127Figure 8-18Cross-Section Photographs IllustratingInsufficient Melting of Solder Joints DuringReflow Soldering. These Solder Joints areLocated Below the Cam of a Socket. .......... 128Figure 8-19Solder Mask Influence .................................. 129IPC-7095CJanuary 2013xFigure 8-20Reliability Test Failure Due to Very LargeVoid ........................................ ....................... 129Figure 8-21Comparison of a Lead-Free (SnAgCu)and Tin/Lead (SnPb) BGA ReflowSolderingProfiles ........................................ .................. 132Figure 8-22Endoscope Photo of a SnAgCu BGASolder Ball ........................................ ............ 133Figure 8-23Comparison of Reflow Soldering Profilesfor Tin/Lead, Backward Compatibility andTotal Lead-Free Board Assemblies .............. 134Figure 8-24Micrograph of a cross-section of a BGASnAgCu solder ball, assembled onto aboard with tin/lead solder paste using thestandard tin/lead reflow soldering SnAgCu solder ball does not melt;black/grey interconnecting fingers arelead-rich grain boundaries; rod shapeparticles are Ag3Sn IMCs; grey particlesare Cu6Sn5 IMCs. ........................................ 134Figure 8-25Micrograph of a cross-section of a BGASnAgCu solder ball, assembled onto aboard with tin/lead solder paste using abackward compatibility reflows solderingprofile. The SnAgCu solder ball hasmelted. ........................................ .................. 134Figure A-1Typical Flow Diagram for VoidAssessment ........................................ .......... 151Figure A-2Voids in BGAs with Crack Started atCorner Lead ........................................ .......... 155Figure A-3Void Diameter Related to Land Size ............ 155TablesTable 3-1Multichip Module Definitions ............................... 6Table 3-2Number of Escapes Size on Two Layers of Circuitry ................ 6Table 3-3Potential Plating or Component TerminationMaterial Properties ........................................ .... 10Table 3-4Example of Semiconductor Cost Predictions ... 12Table 4-1JEDEC Standard JEP95-1/5Allowable Ball Diameter Variations for FBGA ... 20Table 4-2Ball Diameter Sizes for PBGAs ........................ 20Table 4-3Future Ball Size Diameters for DSPBGAs ........ 21Table 4-4Land Size Approximation .................................. 21Table 4-5Land-to-Ball Calculations for Current andFuture BGA Packages (mm) ............................. 22Table 4-6Examples of JEDEC Registered BGAOutlines ........................................ ..................... 22Table 4-7Pb-Free Alloy Variations .................................... 24Table 4-8IPC-4101C FR-4 Property Summaries -Specification Sheets Projected to BetterWithstand Lead-Free Assembly ........................ 32Table 4-9Typical Properties of CommonDielectric Materials for BGA PackageSubstrates ........................................ ................. 34Table 4-10Moisture Classification Level and Floor Life ..... 36Table 5-1Environmental Properties of CommonDielectric Materials ........................................ .... 39Table 5-2Key Attributes for Various Board SurfaceFinishes ........................................ ..................... 41Table 5-3Via Filling/Encroachment to Surface FinishProcess Evaluation ........................................ ... 48Table 5-4Via Fill Options ........................................ .......... 50Table 6-1Number of Conductors Between SolderLands for mm Pitch BGAs ........................ 52Table 6-2Number of Conductors Between SolderLands for mm Pitch BGAs .......................... 52Table 6-3Maximum Solder Land to Pitch Relationship .... 53Table 6-4Escape Strategies for Full Arrays ..................... 57Table 6-5Conductor Routing - mm Pitch ................. 58Table 6-6Conductor Routing - mm Pitch ................... 58Table 6-7Conductor Routing - mm Pitch ................... 58Table 6-8Conductor Routing - mm Pitch ................. 58Table 6-9Conductor Routing - mm Pitch ................... 58Table 6-10 Conductor Routing - mm Pitch ................... 58Table 6-11 Effects of Material Type on Conduction ............ 71Table 6-12 Emissivity Ratings for Certain Materials ........... 71Table 7-1Particle Size Comparisons ................................ 76Table 7-2Example of Solder Paste VolumeRequirements for Ceramic Array Packages ..... 78Table 7-3Profile Comparison Between SnPb and SACAlloys ........................................ ......................... 80Table 7-4Inspection Usage ApplicationRecommendations ........................................ .... 91Table 7-5Field of View for Inspection .............................. 96Table 7-6Void Classification ........................................ ... 103Table 7-7Ball-to-Void Size Image -Comparison for Various Ball Diameters .......... 105Table 7-8C=0 Sampling Plan (Sample Size forSpecific Index Value*) ..................................... 106Table 7-9Repair Process Temperature Profiles forTin Lead Assembly ........................................ .. 116Table 7-10 Repair Process Temperature Profiles forLead-Free Assemblies ..................................... 116Table 8-1Tin/Lead Component Compatibility withLead-Free Reflow Soldering ........................... 121Table 8-2Typical Stand-OffHeights for Tin/Lead Balls (in mm) ................. 128Table 8-3Common Solders, Their Melting Points,Advantages and Drawbacks ........................... 130Table 8-4Comparison of Lead-Free Solder AlloyCompositions in The Sn-Ag-Cu FamilySelection by Various Consortia ....................... 131Table 8-5Types of Lead-Free Assemblies Possible ....... 133Table 8-6Accelerated Testing for End UseEnvironments ........................................ .......... 137Table A-1Corrective Action Indicator for Lands usedwith , or mm Pitch ........................ 152Table A-2Corrective Action Indicator for Lands usedwith , or mm Pitch ........................ 153Table A-3Corrective Action Indicator for Microviain Pad Lands used with , mm Pitch ........................................ ........... 154January 2013IPC-7095CxiDesign and Assembly Process Implementation for BGAs1 SCOPEThis document describes the design and assembly chal-lenges for implementing Ball Grid Array (BGA) and FinePitch BGA (FBGA) technology. The effect of BGA andFBGA on current technology and component types isaddressed, as is the move to lead-free assembly focus on the information contained herein is on criti-cal inspection, repair, and reliability issues associated withBGAs. Throughout this document the word BGA canmean all types and forms of ball/column/bump/pillar gridarray PurposeThe target audiences for this document aremanagers, design and process engineers, and operators andtechnicians who deal with the electronic assembly, inspec-tion, and repair processes. The purpose is to provide usefuland practical information to those who are using BGAs,those who are considering BGA implementation andcompanies who are in the process of transition from stan-dard tin/lead reflow processes to those that use IntentThis document, although not a completerecipe, identifies many of the characteristics that influencethe successful implementation of a robust assembly pro-cess. In many applications, the variation between assemblymethods and materials is reviewed with the intent to high-light significant differences that relate to the quality andreliability of the final product. The accept/reject criteria forBGA assemblies, used in contractual agreements, is estab-lished by J-STD-001 and additional challenge in implementing BGA assemblyprocesses, along with other types of components, is theneed to meet the legislative directives that declare certainmaterials as hazardous to the environment. The require-ments to eliminate these materials from electronic assem-blies have caused component manufacturers to rethink thematerials used for encapsulation, the plating finishes on thecomponents and the metal alloys used in the assemblyattachment APPLICABLE IPC1J-STD-001Requirements for Soldered Electrical and Elec-tronic AssembliesJ-STD-020Handling Requirements for Moisture SensitiveComponentsJ-STD-033Standard for Handling, Packing, Shipping andUse of Moisture/Reflow Sensitive Surface Mount DevicesJ-STD-609Marking and Labeling of Components, PCBsand PCBAs to Identify Lead (Pb), Pb-Free and OtherAttributesIPC-T-50Terms and Definitions for Printed Boards andPrinted Board AssembliesIPC-D-279Design Guidelines for Reliable Surface MountTechnology Printed Board AssembliesIPC-D-356Bare Substrate Electrical Test Information inDigital FormIPC-A-600Acceptability of Printed BoardsIPC-A-610Acceptability of Electronic AssembliesIPC-SM-785Guidelines for Accelerated Reliability Testingof Surface Mount AttachmentsIPC-1601Printed Board Handling and Storage GuidelinesIPC-2221Generic Standard on Printed Board DesignIPC-2581Generic Requirements for Printed Board Assem-bly Products Manufacturing Description Data and TransferMethodologyIPC-2611Generic Requirements for Electronic ProductDocumentationIPC-2614Sectional Requirements for Board FabricationDocumentationIPC-2616Sectiona l Requirements for Assembly Docu-mentationIPC-4554Specification for Immersion Tin Plating forPrinted Circuit BoardsIPC-4761Design Guide for Protection of Printed BoardVia StructuresIPC-7093Design and Assembly Process Implementationfor Bottom Termination ComponentsIPC-7094Design and Assembly Process Implementationfor Flip Chip and Die Size ComponentsIPC-7351Generic Requirements for Surface MountDesign and Land Pattern StandardIPC-7525Stencil Design Guidelines1. 2013IPC-7095C1

Related search results